[Ancillary values of fluorescence in situ hybridization with different gene combination in diagnosis of malignant melanoma].

Objective: To investigate the clinical value of the first multicolor fluorescence in situ hybridization (FISH) assay on multiple genes, and combined with 9p21 and 8q24 evaluation in the differential diagnosis of melanoma. Methods: Fifty-six melanomas and 36 benign melanocytic nevi diagnosed in Fudan University Shanghai Cancer Center from 2017 to 2019 were included. Each specimen was examined by first multicolor FISH assay targeting 6p25 (RREB1), 6q23 (MYB), 11q13 (CCND1) and CEP6, as well as 9p21 (CDKN2A) and 8q24 (MYC). The results of FISH assay in all cases were recorded according to Gerami's criteria. Basing on the sensitivity and specificity of the first FISH assay, the refinement of diagnosis by adding combined 9p21 and 8q24 probes was further evaluated, as well as their association with different clinicopathological features. Results: In 86 cases, the FISH signals were adequate for analysis. Of the 56 melanoma cases, 52 cases were adequate for analysis; 36 cases (69.2%) were positive in the first FISH assay. The most frequent chromosomal anomaly was gain of RREB1 (30/52, 57.7%), followed by gain of CCND1 (20/52, 38.5%), loss of MYB relative to CEP6 (18/52, 34.6%) and gain of RREB1 relative to CEP6 (17/52, 32.7%). The frequency of homozygous deletions in 9p21 was 15.4% (8/52) and gain of 8q24 was 36.5% (19/52). Among the 36 melanocytic nevi cases, FISH results could be accurately evaluated in 34 cases, and none showed a positive result in the first FISH assay or 9p21 and 8q24 FISH analysis. Compared with the first FISH assay, the sensitivity of combination with 9p21 and 8q24 FISH analysis increased from 69.2% to 76.9% (40/52) and the specificity remained 100.0%. Statistical data showed that the rates of FISH positivity in patients with acral-lentiginious melanoma and nodual melanoma subtypes were higher than that in patients with superficial spreading melanoma and lentigo maligna melanoma subtypes, and patients with Breslow thickness>2.0 mm had higher positive FISH frequency than patients with Breslow thickness ≤2.0 mm. Conclusion: Multisite FISH analysis is a highly effective ancillary tool for the differentiation of unequivocal malignant from benign melanocytic lesions. By combining the first FISH assay with CDKN2A and MYC assay, the clinical utility of FISH analysis is further optimized in differential diagnosis of melanoma. Patients with Breslow thickness>2.0 mm, or acral-lentiginious melanoma and nodual melanoma subtypes tend to have higher FISH positivity. There remains a need to further explore the ancillary value of FISH analysis in diagnosis of ambiguous lesions.目的： 探讨多基因组合联合CDKN2A及MYC基因荧光原位杂交（FISH）检测在黑色素瘤中的辅助诊断价值。 方法： 对2017至2019年于复旦大学附属肿瘤医院确诊的56例黑色素瘤及36例良性黑色素细胞痣进行包括6p25（RREB1）、6q23（MYB）、11q13（CCND1）和CEP6基因位点的第一代组合FISH检测及9p21（CDKN2A）、8q24（MYC）基因FISH检测，根据Gerami学者所建立的阳性标准对FISH结果进行判读，分别统计不同基因组合FISH检测在黑色素瘤辅助诊断中的灵敏度及特异度，并进一步分析不同临床病理特征与FISH检测灵敏度的关系。 结果： 56例黑色素瘤病例中有52例可准确判读FISH结果，第一代4色组合FISH检测阳性病例为36例（69.2%），其中最常见的基因异常为RREB1信号扩增（30/52，57.7%），其次分别为CCND1信号扩增（20/52，38.5%）、MYB信号CEP6信号（17/52，32.7%）；进一步联合9p21、8q24及CEP9组合探针检测结果显示CDKN2A纯合性缺失8例（8/52，15.4%），MYC扩增19例（19/52，36.5%）。36例良性黑色素细胞痣病例中共有34例FISH结果可准确判读，第一代4色组合及CDKN2A、MYC基因FISH检测结果均为阴性。联合CDKN2A及MYC基因FISH检测可将在黑色素瘤诊断中的灵敏度从69.2%（36/52）提升至76.9%（40/52），特异度保持为100.0%。52例黑色素瘤病例组中统计分析显示，不同组织学类型之间FISH检测灵敏度差异具有统计学意义（P<0.05），肢端雀斑样型及结节型病例中组合FISH检测的阳性率高于浅表扩散型及恶性雀斑样型病例；且Breslow厚度>2.0 mm病例中FISH检测阳性率显著高于Breslow厚度≤2.0 mm病例。 结论： 多基因组合FISH检测在鉴别良恶性黑色素细胞病变中具有较高临床应用价值，在第一代4色组合FISH检测基础上联合CDKN2A及MYC基因FISH检测可在一定程度提高辅助诊断的灵敏度且保持高度特异度；在Breslow厚度>2.0 mm及肢端雀斑样、结节型黑色素瘤患者中FISH检测阳性率较高。但仍需更多研究进一步探索多基因组合FISH检测在诊断不明确病变中的应用价值。.